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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Annotate Ref in Prog with C types by parsing gcc debug output.
// Conversion of debug output to Go types.
package main
import (
"bytes"
"debug/dwarf"
"debug/elf"
"debug/macho"
"debug/pe"
"encoding/binary"
"errors"
"flag"
"fmt"
"go/ast"
"go/parser"
"go/token"
"internal/xcoff"
"math"
"os"
"strconv"
"strings"
"unicode"
"unicode/utf8"
)
var debugDefine = flag.Bool("debug-define", false, "print relevant #defines")
var debugGcc = flag.Bool("debug-gcc", false, "print gcc invocations")
var nameToC = map[string]string{
"schar": "signed char",
"uchar": "unsigned char",
"ushort": "unsigned short",
"uint": "unsigned int",
"ulong": "unsigned long",
"longlong": "long long",
"ulonglong": "unsigned long long",
"complexfloat": "float _Complex",
"complexdouble": "double _Complex",
}
// cname returns the C name to use for C.s.
// The expansions are listed in nameToC and also
// struct_foo becomes "struct foo", and similarly for
// union and enum.
func cname(s string) string {
if t, ok := nameToC[s]; ok {
return t
}
if strings.HasPrefix(s, "struct_") {
return "struct " + s[len("struct_"):]
}
if strings.HasPrefix(s, "union_") {
return "union " + s[len("union_"):]
}
if strings.HasPrefix(s, "enum_") {
return "enum " + s[len("enum_"):]
}
if strings.HasPrefix(s, "sizeof_") {
return "sizeof(" + cname(s[len("sizeof_"):]) + ")"
}
return s
}
// DiscardCgoDirectives processes the import C preamble, and discards
// all #cgo CFLAGS and LDFLAGS directives, so they don't make their
// way into _cgo_export.h.
func (f *File) DiscardCgoDirectives() {
linesIn := strings.Split(f.Preamble, "\n")
linesOut := make([]string, 0, len(linesIn))
for _, line := range linesIn {
l := strings.TrimSpace(line)
if len(l) < 5 || l[:4] != "#cgo" || !unicode.IsSpace(rune(l[4])) {
linesOut = append(linesOut, line)
} else {
linesOut = append(linesOut, "")
}
}
f.Preamble = strings.Join(linesOut, "\n")
}
// addToFlag appends args to flag. All flags are later written out onto the
// _cgo_flags file for the build system to use.
func (p *Package) addToFlag(flag string, args []string) {
p.CgoFlags[flag] = append(p.CgoFlags[flag], args...)
if flag == "CFLAGS" {
// We'll also need these when preprocessing for dwarf information.
// However, discard any -g options: we need to be able
// to parse the debug info, so stick to what we expect.
for _, arg := range args {
if !strings.HasPrefix(arg, "-g") {
p.GccOptions = append(p.GccOptions, arg)
}
}
}
}
// splitQuoted splits the string s around each instance of one or more consecutive
// white space characters while taking into account quotes and escaping, and
// returns an array of substrings of s or an empty list if s contains only white space.
// Single quotes and double quotes are recognized to prevent splitting within the
// quoted region, and are removed from the resulting substrings. If a quote in s
// isn't closed err will be set and r will have the unclosed argument as the
// last element. The backslash is used for escaping.
//
// For example, the following string:
//
// `a b:"c d" 'e''f' "g\""`
//
// Would be parsed as:
//
// []string{"a", "b:c d", "ef", `g"`}
//
func splitQuoted(s string) (r []string, err error) {
var args []string
arg := make([]rune, len(s))
escaped := false
quoted := false
quote := '\x00'
i := 0
for _, r := range s {
switch {
case escaped:
escaped = false
case r == '\\':
escaped = true
continue
case quote != 0:
if r == quote {
quote = 0
continue
}
case r == '"' || r == '\'':
quoted = true
quote = r
continue
case unicode.IsSpace(r):
if quoted || i > 0 {
quoted = false
args = append(args, string(arg[:i]))
i = 0
}
continue
}
arg[i] = r
i++
}
if quoted || i > 0 {
args = append(args, string(arg[:i]))
}
if quote != 0 {
err = errors.New("unclosed quote")
} else if escaped {
err = errors.New("unfinished escaping")
}
return args, err
}
// Translate rewrites f.AST, the original Go input, to remove
// references to the imported package C, replacing them with
// references to the equivalent Go types, functions, and variables.
func (p *Package) Translate(f *File) {
for _, cref := range f.Ref {
// Convert C.ulong to C.unsigned long, etc.
cref.Name.C = cname(cref.Name.Go)
}
var conv typeConv
conv.Init(p.PtrSize, p.IntSize)
p.loadDefines(f)
p.typedefs = map[string]bool{}
p.typedefList = nil
numTypedefs := -1
for len(p.typedefs) > numTypedefs {
numTypedefs = len(p.typedefs)
// Also ask about any typedefs we've seen so far.
for _, info := range p.typedefList {
n := &Name{
Go: info.typedef,
C: info.typedef,
}
f.Name[info.typedef] = n
f.NamePos[n] = info.pos
}
needType := p.guessKinds(f)
if len(needType) > 0 {
p.loadDWARF(f, &conv, needType)
}
// In godefs mode we're OK with the typedefs, which
// will presumably also be defined in the file, we
// don't want to resolve them to their base types.
if *godefs {
break
}
}
p.prepareNames(f)
if p.rewriteCalls(f) {
// Add `import _cgo_unsafe "unsafe"` after the package statement.
f.Edit.Insert(f.offset(f.AST.Name.End()), "; import _cgo_unsafe \"unsafe\"")
}
p.rewriteRef(f)
}
// loadDefines coerces gcc into spitting out the #defines in use
// in the file f and saves relevant renamings in f.Name[name].Define.
func (p *Package) loadDefines(f *File) {
var b bytes.Buffer
b.WriteString(builtinProlog)
b.WriteString(f.Preamble)
stdout := p.gccDefines(b.Bytes())
for _, line := range strings.Split(stdout, "\n") {
if len(line) < 9 || line[0:7] != "#define" {
continue
}
line = strings.TrimSpace(line[8:])
var key, val string
spaceIndex := strings.Index(line, " ")
tabIndex := strings.Index(line, "\t")
if spaceIndex == -1 && tabIndex == -1 {
continue
} else if tabIndex == -1 || (spaceIndex != -1 && spaceIndex < tabIndex) {
key = line[0:spaceIndex]
val = strings.TrimSpace(line[spaceIndex:])
} else {
key = line[0:tabIndex]
val = strings.TrimSpace(line[tabIndex:])
}
if key == "__clang__" {
p.GccIsClang = true
}
if n := f.Name[key]; n != nil {
if *debugDefine {
fmt.Fprintf(os.Stderr, "#define %s %s\n", key, val)
}
n.Define = val
}
}
}
// guessKinds tricks gcc into revealing the kind of each
// name xxx for the references C.xxx in the Go input.
// The kind is either a constant, type, or variable.
func (p *Package) guessKinds(f *File) []*Name {
// Determine kinds for names we already know about,
// like #defines or 'struct foo', before bothering with gcc.
var names, needType []*Name
optional := map[*Name]bool{}
for _, key := range nameKeys(f.Name) {
n := f.Name[key]
// If we've already found this name as a #define
// and we can translate it as a constant value, do so.
if n.Define != "" {
if i, err := strconv.ParseInt(n.Define, 0, 64); err == nil {
n.Kind = "iconst"
// Turn decimal into hex, just for consistency
// with enum-derived constants. Otherwise
// in the cgo -godefs output half the constants
// are in hex and half are in whatever the #define used.
n.Const = fmt.Sprintf("%#x", i)
} else if n.Define[0] == '\'' {
if _, err := parser.ParseExpr(n.Define); err == nil {
n.Kind = "iconst"
n.Const = n.Define
}
} else if n.Define[0] == '"' {
if _, err := parser.ParseExpr(n.Define); err == nil {
n.Kind = "sconst"
n.Const = n.Define
}
}
if n.IsConst() {
continue
}
}
// If this is a struct, union, or enum type name, no need to guess the kind.
if strings.HasPrefix(n.C, "struct ") || strings.HasPrefix(n.C, "union ") || strings.HasPrefix(n.C, "enum ") {
n.Kind = "type"
needType = append(needType, n)
continue
}
if goos == "darwin" && strings.HasSuffix(n.C, "Ref") {
// For FooRef, find out if FooGetTypeID exists.
s := n.C[:len(n.C)-3] + "GetTypeID"
n := &Name{Go: s, C: s}
names = append(names, n)
optional[n] = true
}
// Otherwise, we'll need to find out from gcc.
names = append(names, n)
}
// Bypass gcc if there's nothing left to find out.
if len(names) == 0 {
return needType
}
// Coerce gcc into telling us whether each name is a type, a value, or undeclared.
// For names, find out whether they are integer constants.
// We used to look at specific warning or error messages here, but that tied the
// behavior too closely to specific versions of the compilers.
// Instead, arrange that we can infer what we need from only the presence or absence
// of an error on a specific line.
//
// For each name, we generate these lines, where xxx is the index in toSniff plus one.
//
// #line xxx "not-declared"
// void __cgo_f_xxx_1(void) { __typeof__(name) *__cgo_undefined__1; }
// #line xxx "not-type"
// void __cgo_f_xxx_2(void) { name *__cgo_undefined__2; }
// #line xxx "not-int-const"
// void __cgo_f_xxx_3(void) { enum { __cgo_undefined__3 = (name)*1 }; }
// #line xxx "not-num-const"
// void __cgo_f_xxx_4(void) { static const double __cgo_undefined__4 = (name); }
// #line xxx "not-str-lit"
// void __cgo_f_xxx_5(void) { static const char __cgo_undefined__5[] = (name); }
//
// If we see an error at not-declared:xxx, the corresponding name is not declared.
// If we see an error at not-type:xxx, the corresponding name is a type.
// If we see an error at not-int-const:xxx, the corresponding name is not an integer constant.
// If we see an error at not-num-const:xxx, the corresponding name is not a number constant.
// If we see an error at not-str-lit:xxx, the corresponding name is not a string literal.
//
// The specific input forms are chosen so that they are valid C syntax regardless of
// whether name denotes a type or an expression.
var b bytes.Buffer
b.WriteString(builtinProlog)
b.WriteString(f.Preamble)
for i, n := range names {
fmt.Fprintf(&b, "#line %d \"not-declared\"\n"+
"void __cgo_f_%d_1(void) { __typeof__(%s) *__cgo_undefined__1; }\n"+
"#line %d \"not-type\"\n"+
"void __cgo_f_%d_2(void) { %s *__cgo_undefined__2; }\n"+
"#line %d \"not-int-const\"\n"+
"void __cgo_f_%d_3(void) { enum { __cgo_undefined__3 = (%s)*1 }; }\n"+
"#line %d \"not-num-const\"\n"+
"void __cgo_f_%d_4(void) { static const double __cgo_undefined__4 = (%s); }\n"+
"#line %d \"not-str-lit\"\n"+
"void __cgo_f_%d_5(void) { static const char __cgo_undefined__5[] = (%s); }\n",
i+1, i+1, n.C,
i+1, i+1, n.C,
i+1, i+1, n.C,
i+1, i+1, n.C,
i+1, i+1, n.C,
)
}
fmt.Fprintf(&b, "#line 1 \"completed\"\n"+
"int __cgo__1 = __cgo__2;\n")
stderr := p.gccErrors(b.Bytes())
if stderr == "" {
fatalf("%s produced no output\non input:\n%s", p.gccBaseCmd()[0], b.Bytes())
}
completed := false
sniff := make([]int, len(names))
const (
notType = 1 << iota
notIntConst
notNumConst
notStrLiteral
notDeclared
)
sawUnmatchedErrors := false
for _, line := range strings.Split(stderr, "\n") {
// Ignore warnings and random comments, with one
// exception: newer GCC versions will sometimes emit
// an error on a macro #define with a note referring
// to where the expansion occurs. We care about where
// the expansion occurs, so in that case treat the note
// as an error.
isError := strings.Contains(line, ": error:")
isErrorNote := strings.Contains(line, ": note:") && sawUnmatchedErrors
if !isError && !isErrorNote {
continue
}
c1 := strings.Index(line, ":")
if c1 < 0 {
continue
}
c2 := strings.Index(line[c1+1:], ":")
if c2 < 0 {
continue
}
c2 += c1 + 1
filename := line[:c1]
i, _ := strconv.Atoi(line[c1+1 : c2])
i--
if i < 0 || i >= len(names) {
if isError {
sawUnmatchedErrors = true
}
continue
}
switch filename {
case "completed":
// Strictly speaking, there is no guarantee that seeing the error at completed:1
// (at the end of the file) means we've seen all the errors from earlier in the file,
// but usually it does. Certainly if we don't see the completed:1 error, we did
// not get all the errors we expected.
completed = true
case "not-declared":
sniff[i] |= notDeclared
case "not-type":
sniff[i] |= notType
case "not-int-const":
sniff[i] |= notIntConst
case "not-num-const":
sniff[i] |= notNumConst
case "not-str-lit":
sniff[i] |= notStrLiteral
default:
if isError {
sawUnmatchedErrors = true
}
continue
}
sawUnmatchedErrors = false
}
if !completed {
fatalf("%s did not produce error at completed:1\non input:\n%s\nfull error output:\n%s", p.gccBaseCmd()[0], b.Bytes(), stderr)
}
for i, n := range names {
switch sniff[i] {
default:
if sniff[i]&notDeclared != 0 && optional[n] {
// Ignore optional undeclared identifiers.
// Don't report an error, and skip adding n to the needType array.
continue
}
error_(f.NamePos[n], "could not determine kind of name for C.%s", fixGo(n.Go))
case notStrLiteral | notType:
n.Kind = "iconst"
case notIntConst | notStrLiteral | notType:
n.Kind = "fconst"
case notIntConst | notNumConst | notType:
n.Kind = "sconst"
case notIntConst | notNumConst | notStrLiteral:
n.Kind = "type"
case notIntConst | notNumConst | notStrLiteral | notType:
n.Kind = "not-type"
}
needType = append(needType, n)
}
if nerrors > 0 {
// Check if compiling the preamble by itself causes any errors,
// because the messages we've printed out so far aren't helpful
// to users debugging preamble mistakes. See issue 8442.
preambleErrors := p.gccErrors([]byte(f.Preamble))
if len(preambleErrors) > 0 {
error_(token.NoPos, "\n%s errors for preamble:\n%s", p.gccBaseCmd()[0], preambleErrors)
}
fatalf("unresolved names")
}
return needType
}
// loadDWARF parses the DWARF debug information generated
// by gcc to learn the details of the constants, variables, and types
// being referred to as C.xxx.
func (p *Package) loadDWARF(f *File, conv *typeConv, names []*Name) {
// Extract the types from the DWARF section of an object
// from a well-formed C program. Gcc only generates DWARF info
// for symbols in the object file, so it is not enough to print the
// preamble and hope the symbols we care about will be there.
// Instead, emit
// __typeof__(names[i]) *__cgo__i;
// for each entry in names and then dereference the type we
// learn for __cgo__i.
var b bytes.Buffer
b.WriteString(builtinProlog)
b.WriteString(f.Preamble)
b.WriteString("#line 1 \"cgo-dwarf-inference\"\n")
for i, n := range names {
fmt.Fprintf(&b, "__typeof__(%s) *__cgo__%d;\n", n.C, i)
if n.Kind == "iconst" {
fmt.Fprintf(&b, "enum { __cgo_enum__%d = %s };\n", i, n.C)
}
}
// We create a data block initialized with the values,
// so we can read them out of the object file.
fmt.Fprintf(&b, "long long __cgodebug_ints[] = {\n")
for _, n := range names {
if n.Kind == "iconst" {
fmt.Fprintf(&b, "\t%s,\n", n.C)
} else {
fmt.Fprintf(&b, "\t0,\n")
}
}
// for the last entry, we cannot use 0, otherwise
// in case all __cgodebug_data is zero initialized,
// LLVM-based gcc will place the it in the __DATA.__common
// zero-filled section (our debug/macho doesn't support
// this)
fmt.Fprintf(&b, "\t1\n")
fmt.Fprintf(&b, "};\n")
// do the same work for floats.
fmt.Fprintf(&b, "double __cgodebug_floats[] = {\n")
for _, n := range names {
if n.Kind == "fconst" {
fmt.Fprintf(&b, "\t%s,\n", n.C)
} else {
fmt.Fprintf(&b, "\t0,\n")
}
}
fmt.Fprintf(&b, "\t1\n")
fmt.Fprintf(&b, "};\n")
// do the same work for strings.
for i, n := range names {
if n.Kind == "sconst" {
fmt.Fprintf(&b, "const char __cgodebug_str__%d[] = %s;\n", i, n.C)
fmt.Fprintf(&b, "const unsigned long long __cgodebug_strlen__%d = sizeof(%s)-1;\n", i, n.C)
}
}
d, ints, floats, strs := p.gccDebug(b.Bytes(), len(names))
// Scan DWARF info for top-level TagVariable entries with AttrName __cgo__i.
types := make([]dwarf.Type, len(names))
r := d.Reader()
for {
e, err := r.Next()
if err != nil {
fatalf("reading DWARF entry: %s", err)
}
if e == nil {
break
}
switch e.Tag {
case dwarf.TagVariable:
name, _ := e.Val(dwarf.AttrName).(string)
typOff, _ := e.Val(dwarf.AttrType).(dwarf.Offset)
if name == "" || typOff == 0 {
if e.Val(dwarf.AttrSpecification) != nil {
// Since we are reading all the DWARF,
// assume we will see the variable elsewhere.
break
}
fatalf("malformed DWARF TagVariable entry")
}
if !strings.HasPrefix(name, "__cgo__") {
break
}
typ, err := d.Type(typOff)
if err != nil {
fatalf("loading DWARF type: %s", err)
}
t, ok := typ.(*dwarf.PtrType)
if !ok || t == nil {
fatalf("internal error: %s has non-pointer type", name)
}
i, err := strconv.Atoi(name[7:])
if err != nil {
fatalf("malformed __cgo__ name: %s", name)
}
types[i] = t.Type
p.recordTypedefs(t.Type, f.NamePos[names[i]])
}
if e.Tag != dwarf.TagCompileUnit {
r.SkipChildren()
}
}
// Record types and typedef information.
for i, n := range names {
if strings.HasSuffix(n.Go, "GetTypeID") && types[i].String() == "func() CFTypeID" {
conv.getTypeIDs[n.Go[:len(n.Go)-9]] = true
}
}
for i, n := range names {
if types[i] == nil {
continue
}
pos := f.NamePos[n]
f, fok := types[i].(*dwarf.FuncType)
if n.Kind != "type" && fok {
n.Kind = "func"
n.FuncType = conv.FuncType(f, pos)
} else {
n.Type = conv.Type(types[i], pos)
switch n.Kind {
case "iconst":
if i < len(ints) {
if _, ok := types[i].(*dwarf.UintType); ok {
n.Const = fmt.Sprintf("%#x", uint64(ints[i]))
} else {
n.Const = fmt.Sprintf("%#x", ints[i])
}
}
case "fconst":
if i >= len(floats) {
break
}
switch base(types[i]).(type) {
case *dwarf.IntType, *dwarf.UintType:
// This has an integer type so it's
// not really a floating point
// constant. This can happen when the
// C compiler complains about using
// the value as an integer constant,
// but not as a general constant.
// Treat this as a variable of the
// appropriate type, not a constant,
// to get C-style type handling,
// avoiding the problem that C permits
// uint64(-1) but Go does not.
// See issue 26066.
n.Kind = "var"
default:
n.Const = fmt.Sprintf("%f", floats[i])
}
case "sconst":
if i < len(strs) {
n.Const = fmt.Sprintf("%q", strs[i])
}
}
}
conv.FinishType(pos)
}
}
// recordTypedefs remembers in p.typedefs all the typedefs used in dtypes and its children.
func (p *Package) recordTypedefs(dtype dwarf.Type, pos token.Pos) {
p.recordTypedefs1(dtype, pos, map[dwarf.Type]bool{})
}
func (p *Package) recordTypedefs1(dtype dwarf.Type, pos token.Pos, visited map[dwarf.Type]bool) {
if dtype == nil {
return
}
if visited[dtype] {
return
}
visited[dtype] = true
switch dt := dtype.(type) {
case *dwarf.TypedefType:
if strings.HasPrefix(dt.Name, "__builtin") {
// Don't look inside builtin types. There be dragons.
return
}
if !p.typedefs[dt.Name] {
p.typedefs[dt.Name] = true
p.typedefList = append(p.typedefList, typedefInfo{dt.Name, pos})
p.recordTypedefs1(dt.Type, pos, visited)
}
case *dwarf.PtrType:
p.recordTypedefs1(dt.Type, pos, visited)
case *dwarf.ArrayType:
p.recordTypedefs1(dt.Type, pos, visited)
case *dwarf.QualType:
p.recordTypedefs1(dt.Type, pos, visited)
case *dwarf.FuncType:
p.recordTypedefs1(dt.ReturnType, pos, visited)
for _, a := range dt.ParamType {
p.recordTypedefs1(a, pos, visited)
}
case *dwarf.StructType:
for _, f := range dt.Field {
p.recordTypedefs1(f.Type, pos, visited)
}
}
}
// prepareNames finalizes the Kind field of not-type names and sets
// the mangled name of all names.
func (p *Package) prepareNames(f *File) {
for _, n := range f.Name {
if n.Kind == "not-type" {
if n.Define == "" {
n.Kind = "var"
} else {
n.Kind = "macro"
n.FuncType = &FuncType{
Result: n.Type,
Go: &ast.FuncType{
Results: &ast.FieldList{List: []*ast.Field{{Type: n.Type.Go}}},
},
}
}
}
p.mangleName(n)
}
}
// mangleName does name mangling to translate names
// from the original Go source files to the names
// used in the final Go files generated by cgo.
func (p *Package) mangleName(n *Name) {
// When using gccgo variables have to be
// exported so that they become global symbols
// that the C code can refer to.
prefix := "_C"
if *gccgo && n.IsVar() {
prefix = "C"
}
n.Mangle = prefix + n.Kind + "_" + n.Go
}
func (f *File) isMangledName(s string) bool {
prefix := "_C"
if strings.HasPrefix(s, prefix) {
t := s[len(prefix):]
for _, k := range nameKinds {
if strings.HasPrefix(t, k+"_") {
return true
}
}
}
return false
}
// rewriteCalls rewrites all calls that pass pointers to check that
// they follow the rules for passing pointers between Go and C.
// This reports whether the package needs to import unsafe as _cgo_unsafe.
func (p *Package) rewriteCalls(f *File) bool {
needsUnsafe := false
// Walk backward so that in C.f1(C.f2()) we rewrite C.f2 first.
for _, call := range f.Calls {
if call.Done {
continue
}
start := f.offset(call.Call.Pos())
end := f.offset(call.Call.End())
str, nu := p.rewriteCall(f, call)
if str != "" {
f.Edit.Replace(start, end, str)
if nu {
needsUnsafe = true
}
}
}
return needsUnsafe
}
// rewriteCall rewrites one call to add pointer checks.
// If any pointer checks are required, we rewrite the call into a
// function literal that calls _cgoCheckPointer for each pointer
// argument and then calls the original function.
// This returns the rewritten call and whether the package needs to
// import unsafe as _cgo_unsafe.
// If it returns the empty string, the call did not need to be rewritten.
func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
// This is a call to C.xxx; set goname to "xxx".
// It may have already been mangled by rewriteName.
var goname string
switch fun := call.Call.Fun.(type) {
case *ast.SelectorExpr:
goname = fun.Sel.Name
case *ast.Ident:
goname = strings.TrimPrefix(fun.Name, "_C2func_")
goname = strings.TrimPrefix(goname, "_Cfunc_")
}
if goname == "" || goname == "malloc" {
return "", false
}
name := f.Name[goname]
if name == nil || name.Kind != "func" {
// Probably a type conversion.
return "", false
}
params := name.FuncType.Params
args := call.Call.Args
// Avoid a crash if the number of arguments doesn't match
// the number of parameters.
// This will be caught when the generated file is compiled.
if len(args) != len(params) {
return "", false
}
any := false
for i, param := range params {
if p.needsPointerCheck(f, param.Go, args[i]) {
any = true
break
}
}
if !any {
return "", false
}
// We need to rewrite this call.
//
// Rewrite C.f(p) to
// func() {
// _cgo0 := p
// _cgoCheckPointer(_cgo0)
// C.f(_cgo0)
// }()
// Using a function literal like this lets us evaluate the
// function arguments only once while doing pointer checks.
// This is particularly useful when passing additional arguments
// to _cgoCheckPointer, as done in checkIndex and checkAddr.
//
// When the function argument is a conversion to unsafe.Pointer,
// we unwrap the conversion before checking the pointer,
// and then wrap again when calling C.f. This lets us check
// the real type of the pointer in some cases. See issue #25941.
//
// When the call to C.f is deferred, we use an additional function
// literal to evaluate the arguments at the right time.
// defer func() func() {
// _cgo0 := p
// return func() {
// _cgoCheckPointer(_cgo0)
// C.f(_cgo0)
// }
// }()()
// This works because the defer statement evaluates the first
// function literal in order to get the function to call.
var sb bytes.Buffer
sb.WriteString("func() ")
if call.Deferred {
sb.WriteString("func() ")
}
needsUnsafe := false
result := false
twoResults := false
if !call.Deferred {
// Check whether this call expects two results.
for _, ref := range f.Ref {
if ref.Expr != &call.Call.Fun {
continue
}
if ref.Context == ctxCall2 {
sb.WriteString("(")
result = true
twoResults = true
}
break
}
// Add the result type, if any.
if name.FuncType.Result != nil {
rtype := p.rewriteUnsafe(name.FuncType.Result.Go)
if rtype != name.FuncType.Result.Go {
needsUnsafe = true
}
sb.WriteString(gofmtLine(rtype))
result = true
}
// Add the second result type, if any.
if twoResults {
if name.FuncType.Result == nil {
// An explicit void result looks odd but it
// seems to be how cgo has worked historically.
sb.WriteString("_Ctype_void")
}
sb.WriteString(", error)")
}
}
sb.WriteString("{ ")
// Define _cgoN for each argument value.
// Write _cgoCheckPointer calls to sbCheck.
var sbCheck bytes.Buffer
for i, param := range params {
origArg := args[i]
arg, nu := p.mangle(f, &args[i])
if nu {
needsUnsafe = true
}
// Use "var x T = ..." syntax to explicitly convert untyped
// constants to the parameter type, to avoid a type mismatch.
ptype := p.rewriteUnsafe(param.Go)
if !p.needsPointerCheck(f, param.Go, args[i]) || param.BadPointer {
if ptype != param.Go {
needsUnsafe = true
}
fmt.Fprintf(&sb, "var _cgo%d %s = %s; ", i,
gofmtLine(ptype), gofmtPos(arg, origArg.Pos()))
continue
}
// Check for &a[i].
if p.checkIndex(&sb, &sbCheck, arg, i) {
continue
}
// Check for &x.
if p.checkAddr(&sb, &sbCheck, arg, i) {
continue
}
fmt.Fprintf(&sb, "_cgo%d := %s; ", i, gofmtPos(arg, origArg.Pos()))
fmt.Fprintf(&sbCheck, "_cgoCheckPointer(_cgo%d); ", i)
}
if call.Deferred {
sb.WriteString("return func() { ")
}
// Write out the calls to _cgoCheckPointer.
sb.WriteString(sbCheck.String())
if result {
sb.WriteString("return ")
}
m, nu := p.mangle(f, &call.Call.Fun)
if nu {
needsUnsafe = true
}
sb.WriteString(gofmtLine(m))
sb.WriteString("(")
for i := range params {
if i > 0 {
sb.WriteString(", ")
}
fmt.Fprintf(&sb, "_cgo%d", i)
}
sb.WriteString("); ")
if call.Deferred {
sb.WriteString("}")
}
sb.WriteString("}")
if call.Deferred {
sb.WriteString("()")
}
sb.WriteString("()")
return sb.String(), needsUnsafe
}
// needsPointerCheck reports whether the type t needs a pointer check.
// This is true if t is a pointer and if the value to which it points
// might contain a pointer.
func (p *Package) needsPointerCheck(f *File, t ast.Expr, arg ast.Expr) bool {
// An untyped nil does not need a pointer check, and when
// _cgoCheckPointer returns the untyped nil the type assertion we
// are going to insert will fail. Easier to just skip nil arguments.
// TODO: Note that this fails if nil is shadowed.
if id, ok := arg.(*ast.Ident); ok && id.Name == "nil" {
return false
}
return p.hasPointer(f, t, true)
}
// hasPointer is used by needsPointerCheck. If top is true it returns
// whether t is or contains a pointer that might point to a pointer.
// If top is false it reports whether t is or contains a pointer.
// f may be nil.
func (p *Package) hasPointer(f *File, t ast.Expr, top bool) bool {
switch t := t.(type) {
case *ast.ArrayType:
if t.Len == nil {
if !top {
return true
}
return p.hasPointer(f, t.Elt, false)
}
return p.hasPointer(f, t.Elt, top)
case *ast.StructType:
for _, field := range t.Fields.List {
if p.hasPointer(f, field.Type, top) {
return true
}
}
return false
case *ast.StarExpr: // Pointer type.
if !top {
return true
}
// Check whether this is a pointer to a C union (or class)
// type that contains a pointer.
if unionWithPointer[t.X] {
return true
}
return p.hasPointer(f, t.X, false)
case *ast.FuncType, *ast.InterfaceType, *ast.MapType, *ast.ChanType:
return true
case *ast.Ident:
// TODO: Handle types defined within function.
for _, d := range p.Decl {
gd, ok := d.(*ast.GenDecl)
if !ok || gd.Tok != token.TYPE {
continue
}
for _, spec := range gd.Specs {
ts, ok := spec.(*ast.TypeSpec)
if !ok {
continue
}
if ts.Name.Name == t.Name {
return p.hasPointer(f, ts.Type, top)
}
}
}
if def := typedef[t.Name]; def != nil {
return p.hasPointer(f, def.Go, top)
}
if t.Name == "string" {
return !top
}
if t.Name == "error" {
return true
}
if goTypes[t.Name] != nil {
return false
}
// We can't figure out the type. Conservative
// approach is to assume it has a pointer.
return true
case *ast.SelectorExpr:
if l, ok := t.X.(*ast.Ident); !ok || l.Name != "C" {
// Type defined in a different package.
// Conservative approach is to assume it has a
// pointer.
return true
}
if f == nil {
// Conservative approach: assume pointer.
return true
}
name := f.Name[t.Sel.Name]
if name != nil && name.Kind == "type" && name.Type != nil && name.Type.Go != nil {
return p.hasPointer(f, name.Type.Go, top)
}
// We can't figure out the type. Conservative
// approach is to assume it has a pointer.
return true
default:
error_(t.Pos(), "could not understand type %s", gofmt(t))
return true
}
}
// mangle replaces references to C names in arg with the mangled names,
// rewriting calls when it finds them.
// It removes the corresponding references in f.Ref and f.Calls, so that we
// don't try to do the replacement again in rewriteRef or rewriteCall.
func (p *Package) mangle(f *File, arg *ast.Expr) (ast.Expr, bool) {
needsUnsafe := false
f.walk(arg, ctxExpr, func(f *File, arg interface{}, context astContext) {
px, ok := arg.(*ast.Expr)
if !ok {
return
}
sel, ok := (*px).(*ast.SelectorExpr)
if ok {
if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
return
}
for _, r := range f.Ref {
if r.Expr == px {
*px = p.rewriteName(f, r)
r.Done = true
break
}
}
return
}
call, ok := (*px).(*ast.CallExpr)
if !ok {
return
}
for _, c := range f.Calls {
if !c.Done && c.Call.Lparen == call.Lparen {
cstr, nu := p.rewriteCall(f, c)
if cstr != "" {
// Smuggle the rewritten call through an ident.
*px = ast.NewIdent(cstr)
if nu {
needsUnsafe = true
}
c.Done = true
}
}
}
})
return *arg, needsUnsafe
}
// checkIndex checks whether arg has the form &a[i], possibly inside
// type conversions. If so, then in the general case it writes
// _cgoIndexNN := a
// _cgoNN := &cgoIndexNN[i] // with type conversions, if any
// to sb, and writes
// _cgoCheckPointer(_cgoNN, _cgoIndexNN)
// to sbCheck, and returns true. If a is a simple variable or field reference,
// it writes
// _cgoIndexNN := &a
// and dereferences the uses of _cgoIndexNN. Taking the address avoids
// making a copy of an array.
//
// This tells _cgoCheckPointer to check the complete contents of the
// slice or array being indexed, but no other part of the memory allocation.
func (p *Package) checkIndex(sb, sbCheck *bytes.Buffer, arg ast.Expr, i int) bool {
// Strip type conversions.
x := arg
for {
c, ok := x.(*ast.CallExpr)
if !ok || len(c.Args) != 1 || !p.isType(c.Fun) {
break
}
x = c.Args[0]
}
u, ok := x.(*ast.UnaryExpr)
if !ok || u.Op != token.AND {
return false
}
index, ok := u.X.(*ast.IndexExpr)
if !ok {
return false
}
addr := ""
deref := ""
if p.isVariable(index.X) {
addr = "&"
deref = "*"
}
fmt.Fprintf(sb, "_cgoIndex%d := %s%s; ", i, addr, gofmtPos(index.X, index.X.Pos()))
origX := index.X
index.X = ast.NewIdent(fmt.Sprintf("_cgoIndex%d", i))
if deref == "*" {
index.X = &ast.StarExpr{X: index.X}
}
fmt.Fprintf(sb, "_cgo%d := %s; ", i, gofmtPos(arg, arg.Pos()))
index.X = origX
fmt.Fprintf(sbCheck, "_cgoCheckPointer(_cgo%d, %s_cgoIndex%d); ", i, deref, i)
return true
}
// checkAddr checks whether arg has the form &x, possibly inside type
// conversions. If so, it writes
// _cgoBaseNN := &x
// _cgoNN := _cgoBaseNN // with type conversions, if any
// to sb, and writes
// _cgoCheckPointer(_cgoBaseNN, true)
// to sbCheck, and returns true. This tells _cgoCheckPointer to check
// just the contents of the pointer being passed, not any other part
// of the memory allocation. This is run after checkIndex, which looks
// for the special case of &a[i], which requires different checks.
func (p *Package) checkAddr(sb, sbCheck *bytes.Buffer, arg ast.Expr, i int) bool {
// Strip type conversions.
px := &arg
for {
c, ok := (*px).(*ast.CallExpr)
if !ok || len(c.Args) != 1 || !p.isType(c.Fun) {
break
}
px = &c.Args[0]
}
if u, ok := (*px).(*ast.UnaryExpr); !ok || u.Op != token.AND {
return false
}
fmt.Fprintf(sb, "_cgoBase%d := %s; ", i, gofmtPos(*px, (*px).Pos()))
origX := *px
*px = ast.NewIdent(fmt.Sprintf("_cgoBase%d", i))
fmt.Fprintf(sb, "_cgo%d := %s; ", i, gofmtPos(arg, arg.Pos()))
*px = origX
// Use "0 == 0" to do the right thing in the unlikely event
// that "true" is shadowed.
fmt.Fprintf(sbCheck, "_cgoCheckPointer(_cgoBase%d, 0 == 0); ", i)
return true
}
// isType reports whether the expression is definitely a type.
// This is conservative--it returns false for an unknown identifier.
func (p *Package) isType(t ast.Expr) bool {
switch t := t.(type) {
case *ast.SelectorExpr:
id, ok := t.X.(*ast.Ident)
if !ok {
return false
}
if id.Name == "unsafe" && t.Sel.Name == "Pointer" {
return true
}
if id.Name == "C" && typedef["_Ctype_"+t.Sel.Name] != nil {
return true
}
return false
case *ast.Ident:
// TODO: This ignores shadowing.
switch t.Name {
case "unsafe.Pointer", "bool", "byte",
"complex64", "complex128",
"error",
"float32", "float64",
"int", "int8", "int16", "int32", "int64",
"rune", "string",
"uint", "uint8", "uint16", "uint32", "uint64", "uintptr":
return true
}
if strings.HasPrefix(t.Name, "_Ctype_") {
return true
}
case *ast.ParenExpr:
return p.isType(t.X)
case *ast.StarExpr:
return p.isType(t.X)
case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType,
*ast.MapType, *ast.ChanType:
return true
}
return false
}
// isVariable reports whether x is a variable, possibly with field references.
func (p *Package) isVariable(x ast.Expr) bool {
switch x := x.(type) {
case *ast.Ident:
return true
case *ast.SelectorExpr:
return p.isVariable(x.X)
case *ast.IndexExpr:
return true
}
return false
}
// rewriteUnsafe returns a version of t with references to unsafe.Pointer
// rewritten to use _cgo_unsafe.Pointer instead.
func (p *Package) rewriteUnsafe(t ast.Expr) ast.Expr {
switch t := t.(type) {
case *ast.Ident:
// We don't see a SelectorExpr for unsafe.Pointer;
// this is created by code in this file.
if t.Name == "unsafe.Pointer" {
return ast.NewIdent("_cgo_unsafe.Pointer")
}
case *ast.ArrayType:
t1 := p.rewriteUnsafe(t.Elt)
if t1 != t.Elt {
r := *t
r.Elt = t1
return &r
}
case *ast.StructType:
changed := false
fields := *t.Fields
fields.List = nil
for _, f := range t.Fields.List {
ft := p.rewriteUnsafe(f.Type)
if ft == f.Type {
fields.List = append(fields.List, f)
} else {
fn := *f
fn.Type = ft
fields.List = append(fields.List, &fn)
changed = true
}
}
if changed {
r := *t
r.Fields = &fields
return &r
}
case *ast.StarExpr: // Pointer type.
x1 := p.rewriteUnsafe(t.X)
if x1 != t.X {
r := *t
r.X = x1
return &r
}
}
return t
}
// rewriteRef rewrites all the C.xxx references in f.AST to refer to the
// Go equivalents, now that we have figured out the meaning of all
// the xxx. In *godefs mode, rewriteRef replaces the names
// with full definitions instead of mangled names.
func (p *Package) rewriteRef(f *File) {
// Keep a list of all the functions, to remove the ones
// only used as expressions and avoid generating bridge
// code for them.
functions := make(map[string]bool)
for _, n := range f.Name {
if n.Kind == "func" {
functions[n.Go] = false
}
}
// Now that we have all the name types filled in,
// scan through the Refs to identify the ones that
// are trying to do a ,err call. Also check that
// functions are only used in calls.
for _, r := range f.Ref {
if r.Name.IsConst() && r.Name.Const == "" {
error_(r.Pos(), "unable to find value of constant C.%s", fixGo(r.Name.Go))
}
if r.Name.Kind == "func" {
switch r.Context {
case ctxCall, ctxCall2:
functions[r.Name.Go] = true
}
}
expr := p.rewriteName(f, r)
if *godefs {
// Substitute definition for mangled type name.
if id, ok := expr.(*ast.Ident); ok {
if t := typedef[id.Name]; t != nil {
expr = t.Go
}
if id.Name == r.Name.Mangle && r.Name.Const != "" {
expr = ast.NewIdent(r.Name.Const)
}
}
}
// Copy position information from old expr into new expr,
// in case expression being replaced is first on line.
// See golang.org/issue/6563.
pos := (*r.Expr).Pos()
if x, ok := expr.(*ast.Ident); ok {
expr = &ast.Ident{NamePos: pos, Name: x.Name}
}
// Change AST, because some later processing depends on it,
// and also because -godefs mode still prints the AST.
old := *r.Expr
*r.Expr = expr
// Record source-level edit for cgo output.
if !r.Done {
// Prepend a space in case the earlier code ends
// with '/', which would give us a "//" comment.
repl := " " + gofmtPos(expr, old.Pos())
end := fset.Position(old.End())
// Subtract 1 from the column if we are going to
// append a close parenthesis. That will set the
// correct column for the following characters.
sub := 0
if r.Name.Kind != "type" {
sub = 1
}
if end.Column > sub {
repl = fmt.Sprintf("%s /*line :%d:%d*/", repl, end.Line, end.Column-sub)
}
if r.Name.Kind != "type" {
repl = "(" + repl + ")"
}
f.Edit.Replace(f.offset(old.Pos()), f.offset(old.End()), repl)
}
}
// Remove functions only used as expressions, so their respective
// bridge functions are not generated.
for name, used := range functions {
if !used {
delete(f.Name, name)
}
}
}
// rewriteName returns the expression used to rewrite a reference.
func (p *Package) rewriteName(f *File, r *Ref) ast.Expr {
var expr ast.Expr = ast.NewIdent(r.Name.Mangle) // default
switch r.Context {
case ctxCall, ctxCall2:
if r.Name.Kind != "func" {
if r.Name.Kind == "type" {
r.Context = ctxType
if r.Name.Type == nil {
error_(r.Pos(), "invalid conversion to C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
break
}
expr = r.Name.Type.Go
break
}
error_(r.Pos(), "call of non-function C.%s", fixGo(r.Name.Go))
break
}
if r.Context == ctxCall2 {
if r.Name.Go == "_CMalloc" {
error_(r.Pos(), "no two-result form for C.malloc")
break
}
// Invent new Name for the two-result function.
n := f.Name["2"+r.Name.Go]
if n == nil {
n = new(Name)
*n = *r.Name
n.AddError = true
n.Mangle = "_C2func_" + n.Go
f.Name["2"+r.Name.Go] = n
}
expr = ast.NewIdent(n.Mangle)
r.Name = n
break
}
case ctxExpr:
switch r.Name.Kind {
case "func":
if builtinDefs[r.Name.C] != "" {
error_(r.Pos(), "use of builtin '%s' not in function call", fixGo(r.Name.C))
}
// Function is being used in an expression, to e.g. pass around a C function pointer.
// Create a new Name for this Ref which causes the variable to be declared in Go land.
fpName := "fp_" + r.Name.Go
name := f.Name[fpName]
if name == nil {
name = &Name{
Go: fpName,
C: r.Name.C,
Kind: "fpvar",
Type: &Type{Size: p.PtrSize, Align: p.PtrSize, C: c("void*"), Go: ast.NewIdent("unsafe.Pointer")},
}
p.mangleName(name)
f.Name[fpName] = name
}
r.Name = name
// Rewrite into call to _Cgo_ptr to prevent assignments. The _Cgo_ptr
// function is defined in out.go and simply returns its argument. See
// issue 7757.
expr = &ast.CallExpr{
Fun: &ast.Ident{NamePos: (*r.Expr).Pos(), Name: "_Cgo_ptr"},
Args: []ast.Expr{ast.NewIdent(name.Mangle)},
}
case "type":
// Okay - might be new(T)
if r.Name.Type == nil {
error_(r.Pos(), "expression C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
break
}
expr = r.Name.Type.Go
case "var":
expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
case "macro":
expr = &ast.CallExpr{Fun: expr}
}
case ctxSelector:
if r.Name.Kind == "var" {
expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
} else {
error_(r.Pos(), "only C variables allowed in selector expression %s", fixGo(r.Name.Go))
}
case ctxType:
if r.Name.Kind != "type" {
error_(r.Pos(), "expression C.%s used as type", fixGo(r.Name.Go))
} else if r.Name.Type == nil {
// Use of C.enum_x, C.struct_x or C.union_x without C definition.
// GCC won't raise an error when using pointers to such unknown types.
error_(r.Pos(), "type C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
} else {
expr = r.Name.Type.Go
}
default:
if r.Name.Kind == "func" {
error_(r.Pos(), "must call C.%s", fixGo(r.Name.Go))
}
}
return expr
}
// gofmtPos returns the gofmt-formatted string for an AST node,
// with a comment setting the position before the node.
func gofmtPos(n ast.Expr, pos token.Pos) string {
s := gofmtLine(n)
p := fset.Position(pos)
if p.Column == 0 {
return s
}
return fmt.Sprintf("/*line :%d:%d*/%s", p.Line, p.Column, s)
}
// gccBaseCmd returns the start of the compiler command line.
// It uses $CC if set, or else $GCC, or else the compiler recorded
// during the initial build as defaultCC.
// defaultCC is defined in zdefaultcc.go, written by cmd/dist.
func (p *Package) gccBaseCmd() []string {
// Use $CC if set, since that's what the build uses.
if ret := strings.Fields(os.Getenv("CC")); len(ret) > 0 {
return ret
}
// Try $GCC if set, since that's what we used to use.
if ret := strings.Fields(os.Getenv("GCC")); len(ret) > 0 {
return ret
}
return strings.Fields(defaultCC(goos, goarch))
}
// gccMachine returns the gcc -m flag to use, either "-m32", "-m64" or "-marm".
func (p *Package) gccMachine() []string {
switch goarch {
case "amd64":
return []string{"-m64"}
case "386":
return []string{"-m32"}
case "arm":
return []string{"-marm"} // not thumb
case "s390":
return []string{"-m31"}
case "s390x":
return []string{"-m64"}
case "mips64", "mips64le":
return []string{"-mabi=64"}
case "mips", "mipsle":
return []string{"-mabi=32"}
}
return nil
}
func gccTmp() string {
return *objDir + "_cgo_.o"
}
// gccCmd returns the gcc command line to use for compiling
// the input.
func (p *Package) gccCmd() []string {
c := append(p.gccBaseCmd(),
"-w", // no warnings
"-Wno-error", // warnings are not errors
"-o"+gccTmp(), // write object to tmp
"-gdwarf-2", // generate DWARF v2 debugging symbols
"-c", // do not link
"-xc", // input language is C
)
if p.GccIsClang {
c = append(c,
"-ferror-limit=0",
// Apple clang version 1.7 (tags/Apple/clang-77) (based on LLVM 2.9svn)
// doesn't have -Wno-unneeded-internal-declaration, so we need yet another
// flag to disable the warning. Yes, really good diagnostics, clang.
"-Wno-unknown-warning-option",
"-Wno-unneeded-internal-declaration",
"-Wno-unused-function",
"-Qunused-arguments",
// Clang embeds prototypes for some builtin functions,
// like malloc and calloc, but all size_t parameters are
// incorrectly typed unsigned long. We work around that
// by disabling the builtin functions (this is safe as
// it won't affect the actual compilation of the C code).
// See: https://golang.org/issue/6506.
"-fno-builtin",
)
}
c = append(c, p.GccOptions...)
c = append(c, p.gccMachine()...)
if goos == "aix" {
c = append(c, "-maix64")
c = append(c, "-mcmodel=large")
}
c = append(c, "-") //read input from standard input
return c
}
// gccDebug runs gcc -gdwarf-2 over the C program stdin and
// returns the corresponding DWARF data and, if present, debug data block.
func (p *Package) gccDebug(stdin []byte, nnames int) (d *dwarf.Data, ints []int64, floats []float64, strs []string) {
runGcc(stdin, p.gccCmd())
isDebugInts := func(s string) bool {
// Some systems use leading _ to denote non-assembly symbols.
return s == "__cgodebug_ints" || s == "___cgodebug_ints"
}
isDebugFloats := func(s string) bool {
// Some systems use leading _ to denote non-assembly symbols.
return s == "__cgodebug_floats" || s == "___cgodebug_floats"
}
indexOfDebugStr := func(s string) int {
// Some systems use leading _ to denote non-assembly symbols.
if strings.HasPrefix(s, "___") {
s = s[1:]
}
if strings.HasPrefix(s, "__cgodebug_str__") {
if n, err := strconv.Atoi(s[len("__cgodebug_str__"):]); err == nil {
return n
}
}
return -1
}
indexOfDebugStrlen := func(s string) int {
// Some systems use leading _ to denote non-assembly symbols.
if strings.HasPrefix(s, "___") {
s = s[1:]
}
if strings.HasPrefix(s, "__cgodebug_strlen__") {
if n, err := strconv.Atoi(s[len("__cgodebug_strlen__"):]); err == nil {
return n
}
}
return -1
}
strs = make([]string, nnames)
strdata := make(map[int]string, nnames)
strlens := make(map[int]int, nnames)
buildStrings := func() {
for n, strlen := range strlens {
data := strdata[n]
if len(data) <= strlen {
fatalf("invalid string literal")
}
strs[n] = data[:strlen]
}
}
if f, err := macho.Open(gccTmp()); err == nil {
defer f.Close()
d, err := f.DWARF()
if err != nil {
fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
}
bo := f.ByteOrder
if f.Symtab != nil {
for i := range f.Symtab.Syms {
s := &f.Symtab.Syms[i]
switch {
case isDebugInts(s.Name):
// Found it. Now find data section.
if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
ints = make([]int64, len(data)/8)
for i := range ints {
ints[i] = int64(bo.Uint64(data[i*8:]))
}
}
}
}
case isDebugFloats(s.Name):
// Found it. Now find data section.
if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
floats = make([]float64, len(data)/8)
for i := range floats {
floats[i] = math.Float64frombits(bo.Uint64(data[i*8:]))
}
}
}
}
default:
if n := indexOfDebugStr(s.Name); n != -1 {
// Found it. Now find data section.
if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
strdata[n] = string(data)
}
}
}
break
}
if n := indexOfDebugStrlen(s.Name); n != -1 {
// Found it. Now find data section.
if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
strlen := bo.Uint64(data[:8])
if strlen > (1<<(uint(p.IntSize*8)-1) - 1) { // greater than MaxInt?
fatalf("string literal too big")
}
strlens[n] = int(strlen)
}
}
}
break
}
}
}
buildStrings()
}
return d, ints, floats, strs
}
if f, err := elf.Open(gccTmp()); err == nil {
defer f.Close()
d, err := f.DWARF()
if err != nil {
fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
}
bo := f.ByteOrder
symtab, err := f.Symbols()
if err == nil {
for i := range symtab {
s := &symtab[i]
switch {
case isDebugInts(s.Name):
// Found it. Now find data section.
if i := int(s.Section); 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
ints = make([]int64, len(data)/8)
for i := range ints {
ints[i] = int64(bo.Uint64(data[i*8:]))
}
}
}
}
case isDebugFloats(s.Name):
// Found it. Now find data section.
if i := int(s.Section); 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
floats = make([]float64, len(data)/8)
for i := range floats {
floats[i] = math.Float64frombits(bo.Uint64(data[i*8:]))
}
}
}
}
default:
if n := indexOfDebugStr(s.Name); n != -1 {
// Found it. Now find data section.
if i := int(s.Section); 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
strdata[n] = string(data)
}
}
}
break
}
if n := indexOfDebugStrlen(s.Name); n != -1 {
// Found it. Now find data section.
if i := int(s.Section); 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value-sect.Addr:]
strlen := bo.Uint64(data[:8])
if strlen > (1<<(uint(p.IntSize*8)-1) - 1) { // greater than MaxInt?
fatalf("string literal too big")
}
strlens[n] = int(strlen)
}
}
}
break
}
}
}
buildStrings()
}
return d, ints, floats, strs
}
if f, err := pe.Open(gccTmp()); err == nil {
defer f.Close()
d, err := f.DWARF()
if err != nil {
fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
}
bo := binary.LittleEndian
for _, s := range f.Symbols {
switch {
case isDebugInts(s.Name):
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
ints = make([]int64, len(data)/8)
for i := range ints {
ints[i] = int64(bo.Uint64(data[i*8:]))
}
}
}
}
case isDebugFloats(s.Name):
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
floats = make([]float64, len(data)/8)
for i := range floats {
floats[i] = math.Float64frombits(bo.Uint64(data[i*8:]))
}
}
}
}
default:
if n := indexOfDebugStr(s.Name); n != -1 {
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
strdata[n] = string(data)
}
}
}
break
}
if n := indexOfDebugStrlen(s.Name); n != -1 {
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
strlen := bo.Uint64(data[:8])
if strlen > (1<<(uint(p.IntSize*8)-1) - 1) { // greater than MaxInt?
fatalf("string literal too big")
}
strlens[n] = int(strlen)
}
}
}
break
}
}
}
buildStrings()
return d, ints, floats, strs
}
if f, err := xcoff.Open(gccTmp()); err == nil {
defer f.Close()
d, err := f.DWARF()
if err != nil {
fatalf("cannot load DWARF output from %s: %v", gccTmp(), err)
}
bo := binary.BigEndian
for _, s := range f.Symbols {
switch {
case isDebugInts(s.Name):
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
ints = make([]int64, len(data)/8)
for i := range ints {
ints[i] = int64(bo.Uint64(data[i*8:]))
}
}
}
}
case isDebugFloats(s.Name):
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
floats = make([]float64, len(data)/8)
for i := range floats {
floats[i] = math.Float64frombits(bo.Uint64(data[i*8:]))
}
}
}
}
default:
if n := indexOfDebugStr(s.Name); n != -1 {
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
strdata[n] = string(data)
}
}
}
break
}
if n := indexOfDebugStrlen(s.Name); n != -1 {
if i := int(s.SectionNumber) - 1; 0 <= i && i < len(f.Sections) {
sect := f.Sections[i]
if s.Value < sect.Size {
if sdat, err := sect.Data(); err == nil {
data := sdat[s.Value:]
strlen := bo.Uint64(data[:8])
if strlen > (1<<(uint(p.IntSize*8)-1) - 1) { // greater than MaxInt?
fatalf("string literal too big")
}
strlens[n] = int(strlen)
}
}
}
break
}
}
}
buildStrings()
return d, ints, floats, strs
}
fatalf("cannot parse gcc output %s as ELF, Mach-O, PE, XCOFF object", gccTmp())
panic("not reached")
}
// gccDefines runs gcc -E -dM -xc - over the C program stdin
// and returns the corresponding standard output, which is the
// #defines that gcc encountered while processing the input
// and its included files.
func (p *Package) gccDefines(stdin []byte) string {
base := append(p.gccBaseCmd(), "-E", "-dM", "-xc")
base = append(base, p.gccMachine()...)
stdout, _ := runGcc(stdin, append(append(base, p.GccOptions...), "-"))
return stdout
}
// gccErrors runs gcc over the C program stdin and returns
// the errors that gcc prints. That is, this function expects
// gcc to fail.
func (p *Package) gccErrors(stdin []byte) string {
// TODO(rsc): require failure
args := p.gccCmd()
// Optimization options can confuse the error messages; remove them.
nargs := make([]string, 0, len(args))
for _, arg := range args {
if !strings.HasPrefix(arg, "-O") {
nargs = append(nargs, arg)
}
}
// Force -O0 optimization but keep the trailing "-" at the end.
nargs = append(nargs, "-O0")
nl := len(nargs)
nargs[nl-2], nargs[nl-1] = nargs[nl-1], nargs[nl-2]
if *debugGcc {
fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(nargs, " "))
os.Stderr.Write(stdin)
fmt.Fprint(os.Stderr, "EOF\n")
}
stdout, stderr, _ := run(stdin, nargs)
if *debugGcc {
os.Stderr.Write(stdout)
os.Stderr.Write(stderr)
}
return string(stderr)
}
// runGcc runs the gcc command line args with stdin on standard input.
// If the command exits with a non-zero exit status, runGcc prints
// details about what was run and exits.
// Otherwise runGcc returns the data written to standard output and standard error.
// Note that for some of the uses we expect useful data back
// on standard error, but for those uses gcc must still exit 0.
func runGcc(stdin []byte, args []string) (string, string) {
if *debugGcc {
fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(args, " "))
os.Stderr.Write(stdin)
fmt.Fprint(os.Stderr, "EOF\n")
}
stdout, stderr, ok := run(stdin, args)
if *debugGcc {
os.Stderr.Write(stdout)
os.Stderr.Write(stderr)
}
if !ok {
os.Stderr.Write(stderr)
os.Exit(2)
}
return string(stdout), string(stderr)
}
// A typeConv is a translator from dwarf types to Go types
// with equivalent memory layout.
type typeConv struct {
// Cache of already-translated or in-progress types.
m map[string]*Type
// Map from types to incomplete pointers to those types.
ptrs map[string][]*Type
// Keys of ptrs in insertion order (deterministic worklist)
// ptrKeys contains exactly the keys in ptrs.
ptrKeys []dwarf.Type
// Type names X for which there exists an XGetTypeID function with type func() CFTypeID.
getTypeIDs map[string]bool
// Predeclared types.
bool ast.Expr
byte ast.Expr // denotes padding
int8, int16, int32, int64 ast.Expr
uint8, uint16, uint32, uint64, uintptr ast.Expr
float32, float64 ast.Expr
complex64, complex128 ast.Expr
void ast.Expr
string ast.Expr
goVoid ast.Expr // _Ctype_void, denotes C's void
goVoidPtr ast.Expr // unsafe.Pointer or *byte
ptrSize int64
intSize int64
}
var tagGen int
var typedef = make(map[string]*Type)
var goIdent = make(map[string]*ast.Ident)
// unionWithPointer is true for a Go type that represents a C union (or class)
// that may contain a pointer. This is used for cgo pointer checking.
var unionWithPointer = make(map[ast.Expr]bool)
func (c *typeConv) Init(ptrSize, intSize int64) {
c.ptrSize = ptrSize
c.intSize = intSize
c.m = make(map[string]*Type)
c.ptrs = make(map[string][]*Type)
c.getTypeIDs = make(map[string]bool)
c.bool = c.Ident("bool")
c.byte = c.Ident("byte")
c.int8 = c.Ident("int8")
c.int16 = c.Ident("int16")
c.int32 = c.Ident("int32")
c.int64 = c.Ident("int64")
c.uint8 = c.Ident("uint8")
c.uint16 = c.Ident("uint16")
c.uint32 = c.Ident("uint32")
c.uint64 = c.Ident("uint64")
c.uintptr = c.Ident("uintptr")
c.float32 = c.Ident("float32")
c.float64 = c.Ident("float64")
c.complex64 = c.Ident("complex64")
c.complex128 = c.Ident("complex128")
c.void = c.Ident("void")
c.string = c.Ident("string")
c.goVoid = c.Ident("_Ctype_void")
// Normally cgo translates void* to unsafe.Pointer,
// but for historical reasons -godefs uses *byte instead.
if *godefs {
c.goVoidPtr = &ast.StarExpr{X: c.byte}
} else {
c.goVoidPtr = c.Ident("unsafe.Pointer")
}
}
// base strips away qualifiers and typedefs to get the underlying type
func base(dt dwarf.Type) dwarf.Type {
for {
if d, ok := dt.(*dwarf.QualType); ok {
dt = d.Type
continue
}
if d, ok := dt.(*dwarf.TypedefType); ok {
dt = d.Type
continue
}
break
}
return dt
}
// unqual strips away qualifiers from a DWARF type.
// In general we don't care about top-level qualifiers.
func unqual(dt dwarf.Type) dwarf.Type {
for {
if d, ok := dt.(*dwarf.QualType); ok {
dt = d.Type
} else {
break
}
}
return dt
}
// Map from dwarf text names to aliases we use in package "C".
var dwarfToName = map[string]string{
"long int": "long",
"long unsigned int": "ulong",
"unsigned int": "uint",
"short unsigned int": "ushort",
"unsigned short": "ushort", // Used by Clang; issue 13129.
"short int": "short",
"long long int": "longlong",
"long long unsigned int": "ulonglong",
"signed char": "schar",
"unsigned char": "uchar",
}
const signedDelta = 64
// String returns the current type representation. Format arguments
// are assembled within this method so that any changes in mutable
// values are taken into account.
func (tr *TypeRepr) String() string {
if len(tr.Repr) == 0 {
return ""
}
if len(tr.FormatArgs) == 0 {
return tr.Repr
}
return fmt.Sprintf(tr.Repr, tr.FormatArgs...)
}
// Empty reports whether the result of String would be "".
func (tr *TypeRepr) Empty() bool {
return len(tr.Repr) == 0
}
// Set modifies the type representation.
// If fargs are provided, repr is used as a format for fmt.Sprintf.
// Otherwise, repr is used unprocessed as the type representation.
func (tr *TypeRepr) Set(repr string, fargs ...interface{}) {
tr.Repr = repr
tr.FormatArgs = fargs
}
// FinishType completes any outstanding type mapping work.
// In particular, it resolves incomplete pointer types.
func (c *typeConv) FinishType(pos token.Pos) {
// Completing one pointer type might produce more to complete.
// Keep looping until they're all done.
for len(c.ptrKeys) > 0 {
dtype := c.ptrKeys[0]
dtypeKey := dtype.String()
c.ptrKeys = c.ptrKeys[1:]
ptrs := c.ptrs[dtypeKey]
delete(c.ptrs, dtypeKey)
// Note Type might invalidate c.ptrs[dtypeKey].
t := c.Type(dtype, pos)
for _, ptr := range ptrs {
ptr.Go.(*ast.StarExpr).X = t.Go
ptr.C.Set("%s*", t.C)
}
}
}
// Type returns a *Type with the same memory layout as
// dtype when used as the type of a variable or a struct field.
func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
// Always recompute bad pointer typedefs, as the set of such
// typedefs changes as we see more types.
checkCache := true
if dtt, ok := dtype.(*dwarf.TypedefType); ok && c.badPointerTypedef(dtt) {
checkCache = false
}
key := dtype.String()
if checkCache {
if t, ok := c.m[key]; ok {
if t.Go == nil {
fatalf("%s: type conversion loop at %s", lineno(pos), dtype)
}
return t
}
}
t := new(Type)
t.Size = dtype.Size() // note: wrong for array of pointers, corrected below
t.Align = -1
t.C = &TypeRepr{Repr: dtype.Common().Name}
c.m[key] = t
switch dt := dtype.(type) {
default:
fatalf("%s: unexpected type: %s", lineno(pos), dtype)
case *dwarf.AddrType:
if t.Size != c.ptrSize {
fatalf("%s: unexpected: %d-byte address type - %s", lineno(pos), t.Size, dtype)
}
t.Go = c.uintptr
t.Align = t.Size
case *dwarf.ArrayType:
if dt.StrideBitSize > 0 {
// Cannot represent bit-sized elements in Go.
t.Go = c.Opaque(t.Size)
break
}
count := dt.Count
if count == -1 {
// Indicates flexible array member, which Go doesn't support.
// Translate to zero-length array instead.
count = 0
}
sub := c.Type(dt.Type, pos)
t.Align = sub.Align
t.Go = &ast.ArrayType{
Len: c.intExpr(count),
Elt: sub.Go,
}
// Recalculate t.Size now that we know sub.Size.
t.Size = count * sub.Size
t.C.Set("__typeof__(%s[%d])", sub.C, dt.Count)
case *dwarf.BoolType:
t.Go = c.bool
t.Align = 1
case *dwarf.CharType:
if t.Size != 1 {
fatalf("%s: unexpected: %d-byte char type - %s", lineno(pos), t.Size, dtype)
}
t.Go = c.int8
t.Align = 1
case *dwarf.EnumType:
if t.Align = t.Size; t.Align >= c.ptrSize {
t.Align = c.ptrSize
}
t.C.Set("enum " + dt.EnumName)
signed := 0
t.EnumValues = make(map[string]int64)
for _, ev := range dt.Val {
t.EnumValues[ev.Name] = ev.Val
if ev.Val < 0 {
signed = signedDelta
}
}
switch t.Size + int64(signed) {
default:
fatalf("%s: unexpected: %d-byte enum type - %s", lineno(pos), t.Size, dtype)
case 1:
t.Go = c.uint8
case 2:
t.Go = c.uint16
case 4:
t.Go = c.uint32
case 8:
t.Go = c.uint64
case 1 + signedDelta:
t.Go = c.int8
case 2 + signedDelta:
t.Go = c.int16
case 4 + signedDelta:
t.Go = c.int32
case 8 + signedDelta:
t.Go = c.int64
}
case *dwarf.FloatType:
switch t.Size {
default:
fatalf("%s: unexpected: %d-byte float type - %s", lineno(pos), t.Size, dtype)
case 4:
t.Go = c.float32
case 8:
t.Go = c.float64
}
if t.Align = t.Size; t.Align >= c.ptrSize {
t.Align = c.ptrSize
}
case *dwarf.ComplexType:
switch t.Size {
default:
fatalf("%s: unexpected: %d-byte complex type - %s", lineno(pos), t.Size, dtype)
case 8:
t.Go = c.complex64
case 16:
t.Go = c.complex128
}
if t.Align = t.Size / 2; t.Align >= c.ptrSize {
t.Align = c.ptrSize
}
case *dwarf.FuncType:
// No attempt at translation: would enable calls
// directly between worlds, but we need to moderate those.
t.Go = c.uintptr
t.Align = c.ptrSize
case *dwarf.IntType:
if dt.BitSize > 0 {
fatalf("%s: unexpected: %d-bit int type - %s", lineno(pos), dt.BitSize, dtype)
}
switch t.Size {
default:
fatalf("%s: unexpected: %d-byte int type - %s", lineno(pos), t.Size, dtype)
case 1:
t.Go = c.int8
case 2:
t.Go = c.int16
case 4:
t.Go = c.int32
case 8:
t.Go = c.int64
case 16:
t.Go = &ast.ArrayType{
Len: c.intExpr(t.Size),
Elt: c.uint8,
}
}
if t.Align = t.Size; t.Align >= c.ptrSize {
t.Align = c.ptrSize
}
case *dwarf.PtrType:
// Clang doesn't emit DW_AT_byte_size for pointer types.
if t.Size != c.ptrSize && t.Size != -1 {
fatalf("%s: unexpected: %d-byte pointer type - %s", lineno(pos), t.Size, dtype)
}
t.Size = c.ptrSize
t.Align = c.ptrSize
if _, ok := base(dt.Type).(*dwarf.VoidType); ok {
t.Go = c.goVoidPtr
t.C.Set("void*")
dq := dt.Type
for {
if d, ok := dq.(*dwarf.QualType); ok {
t.C.Set(d.Qual + " " + t.C.String())
dq = d.Type
} else {
break
}
}
break
}
// Placeholder initialization; completed in FinishType.
t.Go = &ast.StarExpr{}
t.C.Set("<incomplete>*")
key := dt.Type.String()
if _, ok := c.ptrs[key]; !ok {
c.ptrKeys = append(c.ptrKeys, dt.Type)
}
c.ptrs[key] = append(c.ptrs[key], t)
case *dwarf.QualType:
t1 := c.Type(dt.Type, pos)
t.Size = t1.Size
t.Align = t1.Align
t.Go = t1.Go
if unionWithPointer[t1.Go] {
unionWithPointer[t.Go] = true
}
t.EnumValues = nil
t.Typedef = ""
t.C.Set("%s "+dt.Qual, t1.C)
return t
case *dwarf.StructType:
// Convert to Go struct, being careful about alignment.
// Have to give it a name to simulate C "struct foo" references.
tag := dt.StructName
if dt.ByteSize < 0 && tag == "" { // opaque unnamed struct - should not be possible
break
}
if tag == "" {
tag = "__" + strconv.Itoa(tagGen)
tagGen++
} else if t.C.Empty() {
t.C.Set(dt.Kind + " " + tag)
}
name := c.Ident("_Ctype_" + dt.Kind + "_" + tag)
t.Go = name // publish before recursive calls
goIdent[name.Name] = name
if dt.ByteSize < 0 {
// Size calculation in c.Struct/c.Opaque will die with size=-1 (unknown),
// so execute the basic things that the struct case would do
// other than try to determine a Go representation.
tt := *t
tt.C = &TypeRepr{"%s %s", []interface{}{dt.Kind, tag}}
tt.Go = c.Ident("struct{}")
typedef[name.Name] = &tt
break
}
switch dt.Kind {
case "class", "union":
t.Go = c.Opaque(t.Size)
if c.dwarfHasPointer(dt, pos) {
unionWithPointer[t.Go] = true
}
if t.C.Empty() {
t.C.Set("__typeof__(unsigned char[%d])", t.Size)
}
t.Align = 1 // TODO: should probably base this on field alignment.
typedef[name.Name] = t
case "struct":
g, csyntax, align := c.Struct(dt, pos)
if t.C.Empty() {
t.C.Set(csyntax)
}
t.Align = align
tt := *t
if tag != "" {
tt.C = &TypeRepr{"struct %s", []interface{}{tag}}
}
tt.Go = g
typedef[name.Name] = &tt
}
case *dwarf.TypedefType:
// Record typedef for printing.
if dt.Name == "_GoString_" {
// Special C name for Go string type.
// Knows string layout used by compilers: pointer plus length,
// which rounds up to 2 pointers after alignment.
t.Go = c.string
t.Size = c.ptrSize * 2
t.Align = c.ptrSize
break
}
if dt.Name == "_GoBytes_" {
// Special C name for Go []byte type.
// Knows slice layout used by compilers: pointer, length, cap.
t.Go = c.Ident("[]byte")
t.Size = c.ptrSize + 4 + 4
t.Align = c.ptrSize
break
}
name := c.Ident("_Ctype_" + dt.Name)
goIdent[name.Name] = name
sub := c.Type(dt.Type, pos)
if c.badPointerTypedef(dt) {
// Treat this typedef as a uintptr.
s := *sub
s.Go = c.uintptr
s.BadPointer = true
sub = &s
// Make sure we update any previously computed type.
if oldType := typedef[name.Name]; oldType != nil {
oldType.Go = sub.Go
oldType.BadPointer = true
}
}
t.Go = name
t.BadPointer = sub.BadPointer
if unionWithPointer[sub.Go] {
unionWithPointer[t.Go] = true
}
t.Size = sub.Size
t.Align = sub.Align
oldType := typedef[name.Name]
if oldType == nil {
tt := *t
tt.Go = sub.Go
tt.BadPointer = sub.BadPointer
typedef[name.Name] = &tt
}
// If sub.Go.Name is "_Ctype_struct_foo" or "_Ctype_union_foo" or "_Ctype_class_foo",
// use that as the Go form for this typedef too, so that the typedef will be interchangeable
// with the base type.
// In -godefs mode, do this for all typedefs.
if isStructUnionClass(sub.Go) || *godefs {
t.Go = sub.Go
if isStructUnionClass(sub.Go) {
// Use the typedef name for C code.
typedef[sub.Go.(*ast.Ident).Name].C = t.C
}
// If we've seen this typedef before, and it
// was an anonymous struct/union/class before
// too, use the old definition.
// TODO: it would be safer to only do this if
// we verify that the types are the same.
if oldType != nil && isStructUnionClass(oldType.Go) {
t.Go = oldType.Go
}
}
case *dwarf.UcharType:
if t.Size != 1 {
fatalf("%s: unexpected: %d-byte uchar type - %s", lineno(pos), t.Size, dtype)
}
t.Go = c.uint8
t.Align = 1
case *dwarf.UintType:
if dt.BitSize > 0 {
fatalf("%s: unexpected: %d-bit uint type - %s", lineno(pos), dt.BitSize, dtype)
}
switch t.Size {
default:
fatalf("%s: unexpected: %d-byte uint type - %s", lineno(pos), t.Size, dtype)
case 1:
t.Go = c.uint8
case 2:
t.Go = c.uint16
case 4:
t.Go = c.uint32
case 8:
t.Go = c.uint64
case 16:
t.Go = &ast.ArrayType{
Len: c.intExpr(t.Size),
Elt: c.uint8,
}
}
if t.Align = t.Size; t.Align >= c.ptrSize {
t.Align = c.ptrSize
}
case *dwarf.VoidType:
t.Go = c.goVoid
t.C.Set("void")
t.Align = 1
}
switch dtype.(type) {
case *dwarf.AddrType, *dwarf.BoolType, *dwarf.CharType, *dwarf.ComplexType, *dwarf.IntType, *dwarf.FloatType, *dwarf.UcharType, *dwarf.UintType:
s := dtype.Common().Name
if s != "" {
if ss, ok := dwarfToName[s]; ok {
s = ss
}
s = strings.Replace(s, " ", "", -1)
name := c.Ident("_Ctype_" + s)
tt := *t
typedef[name.Name] = &tt
if !*godefs {
t.Go = name
}
}
}
if t.Size < 0 {
// Unsized types are [0]byte, unless they're typedefs of other types
// or structs with tags.
// if so, use the name we've already defined.
t.Size = 0
switch dt := dtype.(type) {
case *dwarf.TypedefType:
// ok
case *dwarf.StructType:
if dt.StructName != "" {
break
}
t.Go = c.Opaque(0)
default:
t.Go = c.Opaque(0)
}
if t.C.Empty() {
t.C.Set("void")
}
}
if t.C.Empty() {
fatalf("%s: internal error: did not create C name for %s", lineno(pos), dtype)
}
return t
}
// isStructUnionClass reports whether the type described by the Go syntax x
// is a struct, union, or class with a tag.
func isStructUnionClass(x ast.Expr) bool {
id, ok := x.(*ast.Ident)
if !ok {
return false
}
name := id.Name
return strings.HasPrefix(name, "_Ctype_struct_") ||
strings.HasPrefix(name, "_Ctype_union_") ||
strings.HasPrefix(name, "_Ctype_class_")
}
// FuncArg returns a Go type with the same memory layout as
// dtype when used as the type of a C function argument.
func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type {
t := c.Type(unqual(dtype), pos)
switch dt := dtype.(type) {
case *dwarf.ArrayType:
// Arrays are passed implicitly as pointers in C.
// In Go, we must be explicit.
tr := &TypeRepr{}
tr.Set("%s*", t.C)
return &Type{
Size: c.ptrSize,
Align: c.ptrSize,
Go: &ast.StarExpr{X: t.Go},
C: tr,
}
case *dwarf.TypedefType:
// C has much more relaxed rules than Go for
// implicit type conversions. When the parameter
// is type T defined as *X, simulate a little of the
// laxness of C by making the argument *X instead of T.
if ptr, ok := base(dt.Type).(*dwarf.PtrType); ok {
// Unless the typedef happens to point to void* since
// Go has special rules around using unsafe.Pointer.
if _, void := base(ptr.Type).(*dwarf.VoidType); void {
break
}
// ...or the typedef is one in which we expect bad pointers.
// It will be a uintptr instead of *X.
if c.baseBadPointerTypedef(dt) {
break
}
t = c.Type(ptr, pos)
if t == nil {
return nil
}
// For a struct/union/class, remember the C spelling,
// in case it has __attribute__((unavailable)).
// See issue 2888.
if isStructUnionClass(t.Go) {
t.Typedef = dt.Name
}
}
}
return t
}
// FuncType returns the Go type analogous to dtype.
// There is no guarantee about matching memory layout.
func (c *typeConv) FuncType(dtype *dwarf.FuncType, pos token.Pos) *FuncType {
p := make([]*Type, len(dtype.ParamType))
gp := make([]*ast.Field, len(dtype.ParamType))
for i, f := range dtype.ParamType {
// gcc's DWARF generator outputs a single DotDotDotType parameter for
// function pointers that specify no parameters (e.g. void
// (*__cgo_0)()). Treat this special case as void. This case is
// invalid according to ISO C anyway (i.e. void (*__cgo_1)(...) is not
// legal).
if _, ok := f.(*dwarf.DotDotDotType); ok && i == 0 {
p, gp = nil, nil
break
}
p[i] = c.FuncArg(f, pos)
gp[i] = &ast.Field{Type: p[i].Go}
}
var r *Type
var gr []*ast.Field
if _, ok := base(dtype.ReturnType).(*dwarf.VoidType); ok {
gr = []*ast.Field{{Type: c.goVoid}}
} else if dtype.ReturnType != nil {
r = c.Type(unqual(dtype.ReturnType), pos)
gr = []*ast.Field{{Type: r.Go}}
}
return &FuncType{
Params: p,
Result: r,
Go: &ast.FuncType{
Params: &ast.FieldList{List: gp},
Results: &ast.FieldList{List: gr},
},
}
}
// Identifier
func (c *typeConv) Ident(s string) *ast.Ident {
return ast.NewIdent(s)
}
// Opaque type of n bytes.
func (c *typeConv) Opaque(n int64) ast.Expr {
return &ast.ArrayType{
Len: c.intExpr(n),
Elt: c.byte,
}
}
// Expr for integer n.
func (c *typeConv) intExpr(n int64) ast.Expr {
return &ast.BasicLit{
Kind: token.INT,
Value: strconv.FormatInt(n, 10),
}
}
// Add padding of given size to fld.
func (c *typeConv) pad(fld []*ast.Field, sizes []int64, size int64) ([]*ast.Field, []int64) {
n := len(fld)
fld = fld[0 : n+1]
fld[n] = &ast.Field{Names: []*ast.Ident{c.Ident("_")}, Type: c.Opaque(size)}
sizes = sizes[0 : n+1]
sizes[n] = size
return fld, sizes
}
// Struct conversion: return Go and (gc) C syntax for type.
func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.StructType, csyntax string, align int64) {
// Minimum alignment for a struct is 1 byte.
align = 1
var buf bytes.Buffer
buf.WriteString("struct {")
fld := make([]*ast.Field, 0, 2*len(dt.Field)+1) // enough for padding around every field
sizes := make([]int64, 0, 2*len(dt.Field)+1)
off := int64(0)
// Rename struct fields that happen to be named Go keywords into
// _{keyword}. Create a map from C ident -> Go ident. The Go ident will
// be mangled. Any existing identifier that already has the same name on
// the C-side will cause the Go-mangled version to be prefixed with _.
// (e.g. in a struct with fields '_type' and 'type', the latter would be
// rendered as '__type' in Go).
ident := make(map[string]string)
used := make(map[string]bool)
for _, f := range dt.Field {
ident[f.Name] = f.Name
used[f.Name] = true
}
if !*godefs {
for cid, goid := range ident {
if token.Lookup(goid).IsKeyword() {
// Avoid keyword
goid = "_" + goid
// Also avoid existing fields
for _, exist := used[goid]; exist; _, exist = used[goid] {
goid = "_" + goid
}
used[goid] = true
ident[cid] = goid
}
}
}
anon := 0
for _, f := range dt.Field {
name := f.Name
ft := f.Type
// In godefs mode, if this field is a C11
// anonymous union then treat the first field in the
// union as the field in the struct. This handles
// cases like the glibc <sys/resource.h> file; see
// issue 6677.
if *godefs {
if st, ok := f.Type.(*dwarf.StructType); ok && name == "" && st.Kind == "union" && len(st.Field) > 0 && !used[st.Field[0].Name] {
name = st.Field[0].Name
ident[name] = name
ft = st.Field[0].Type
}
}
// TODO: Handle fields that are anonymous structs by
// promoting the fields of the inner struct.
t := c.Type(ft, pos)
tgo := t.Go
size := t.Size
talign := t.Align
if f.BitSize > 0 {
switch f.BitSize {
case 8, 16, 32, 64:
default:
continue
}
size = f.BitSize / 8
name := tgo.(*ast.Ident).String()
if strings.HasPrefix(name, "int") {
name = "int"
} else {
name = "uint"
}
tgo = ast.NewIdent(name + fmt.Sprint(f.BitSize))
talign = size
}
if talign > 0 && f.ByteOffset%talign != 0 {
// Drop misaligned fields, the same way we drop integer bit fields.
// The goal is to make available what can be made available.
// Otherwise one bad and unneeded field in an otherwise okay struct
// makes the whole program not compile. Much of the time these
// structs are in system headers that cannot be corrected.
continue
}
// Round off up to talign, assumed to be a power of 2.
off = (off + talign - 1) &^ (talign - 1)
if f.ByteOffset > off {
fld, sizes = c.pad(fld, sizes, f.ByteOffset-off)
off = f.ByteOffset
}
if f.ByteOffset < off {
// Drop a packed field that we can't represent.
continue
}
n := len(fld)
fld = fld[0 : n+1]
if name == "" {
name = fmt.Sprintf("anon%d", anon)
anon++
ident[name] = name
}
fld[n] = &ast.Field{Names: []*ast.Ident{c.Ident(ident[name])}, Type: tgo}
sizes = sizes[0 : n+1]
sizes[n] = size
off += size
buf.WriteString(t.C.String())
buf.WriteString(" ")
buf.WriteString(name)
buf.WriteString("; ")
if talign > align {
align = talign
}
}
if off < dt.ByteSize {
fld, sizes = c.pad(fld, sizes, dt.ByteSize-off)
off = dt.ByteSize
}
// If the last field in a non-zero-sized struct is zero-sized
// the compiler is going to pad it by one (see issue 9401).
// We can't permit that, because then the size of the Go
// struct will not be the same as the size of the C struct.
// Our only option in such a case is to remove the field,
// which means that it cannot be referenced from Go.
for off > 0 && sizes[len(sizes)-1] == 0 {
n := len(sizes)
fld = fld[0 : n-1]
sizes = sizes[0 : n-1]
}
if off != dt.ByteSize {
fatalf("%s: struct size calculation error off=%d bytesize=%d", lineno(pos), off, dt.ByteSize)
}
buf.WriteString("}")
csyntax = buf.String()
if *godefs {
godefsFields(fld)
}
expr = &ast.StructType{Fields: &ast.FieldList{List: fld}}
return
}
// dwarfHasPointer reports whether the DWARF type dt contains a pointer.
func (c *typeConv) dwarfHasPointer(dt dwarf.Type, pos token.Pos) bool {
switch dt := dt.(type) {
default:
fatalf("%s: unexpected type: %s", lineno(pos), dt)
return false
case *dwarf.AddrType, *dwarf.BoolType, *dwarf.CharType, *dwarf.EnumType,
*dwarf.FloatType, *dwarf.ComplexType, *dwarf.FuncType,
*dwarf.IntType, *dwarf.UcharType, *dwarf.UintType, *dwarf.VoidType:
return false
case *dwarf.ArrayType:
return c.dwarfHasPointer(dt.Type, pos)
case *dwarf.PtrType:
return true
case *dwarf.QualType:
return c.dwarfHasPointer(dt.Type, pos)
case *dwarf.StructType:
for _, f := range dt.Field {
if c.dwarfHasPointer(f.Type, pos) {
return true
}
}
return false
case *dwarf.TypedefType:
if dt.Name == "_GoString_" || dt.Name == "_GoBytes_" {
return true
}
return c.dwarfHasPointer(dt.Type, pos)
}
}
func upper(s string) string {
if s == "" {
return ""
}
r, size := utf8.DecodeRuneInString(s)
if r == '_' {
return "X" + s
}
return string(unicode.ToUpper(r)) + s[size:]
}
// godefsFields rewrites field names for use in Go or C definitions.
// It strips leading common prefixes (like tv_ in tv_sec, tv_usec)
// converts names to upper case, and rewrites _ into Pad_godefs_n,
// so that all fields are exported.
func godefsFields(fld []*ast.Field) {
prefix := fieldPrefix(fld)
npad := 0
for _, f := range fld {
for _, n := range f.Names {
if n.Name != prefix {
n.Name = strings.TrimPrefix(n.Name, prefix)
}
if n.Name == "_" {
// Use exported name instead.
n.Name = "Pad_cgo_" + strconv.Itoa(npad)
npad++
}
n.Name = upper(n.Name)
}
}
}
// fieldPrefix returns the prefix that should be removed from all the
// field names when generating the C or Go code. For generated
// C, we leave the names as is (tv_sec, tv_usec), since that's what
// people are used to seeing in C. For generated Go code, such as
// package syscall's data structures, we drop a common prefix
// (so sec, usec, which will get turned into Sec, Usec for exporting).
func fieldPrefix(fld []*ast.Field) string {
prefix := ""
for _, f := range fld {
for _, n := range f.Names {
// Ignore field names that don't have the prefix we're
// looking for. It is common in C headers to have fields
// named, say, _pad in an otherwise prefixed header.
// If the struct has 3 fields tv_sec, tv_usec, _pad1, then we
// still want to remove the tv_ prefix.
// The check for "orig_" here handles orig_eax in the
// x86 ptrace register sets, which otherwise have all fields
// with reg_ prefixes.
if strings.HasPrefix(n.Name, "orig_") || strings.HasPrefix(n.Name, "_") {
continue
}
i := strings.Index(n.Name, "_")
if i < 0 {
continue
}
if prefix == "" {
prefix = n.Name[:i+1]
} else if prefix != n.Name[:i+1] {
return ""
}
}
}
return prefix
}
// badPointerTypedef reports whether t is a C typedef that should not be considered a pointer in Go.
// A typedef is bad if C code sometimes stores non-pointers in this type.
// TODO: Currently our best solution is to find these manually and list them as
// they come up. A better solution is desired.
func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
if c.badCFType(dt) {
return true
}
if c.badJNI(dt) {
return true
}
if c.badEGLDisplay(dt) {
return true
}
return false
}
// baseBadPointerTypedef reports whether the base of a chain of typedefs is a bad typedef
// as badPointerTypedef reports.
func (c *typeConv) baseBadPointerTypedef(dt *dwarf.TypedefType) bool {
for {
if t, ok := dt.Type.(*dwarf.TypedefType); ok {
dt = t
continue
}
break
}
return c.badPointerTypedef(dt)
}
func (c *typeConv) badCFType(dt *dwarf.TypedefType) bool {
// The real bad types are CFNumberRef and CFDateRef.
// Sometimes non-pointers are stored in these types.
// CFTypeRef is a supertype of those, so it can have bad pointers in it as well.
// We return true for the other *Ref types just so casting between them is easier.
// We identify the correct set of types as those ending in Ref and for which
// there exists a corresponding GetTypeID function.
// See comment below for details about the bad pointers.
if goos != "darwin" {
return false
}
s := dt.Name
if !strings.HasSuffix(s, "Ref") {
return false
}
s = s[:len(s)-3]
if s == "CFType" {
return true
}
if c.getTypeIDs[s] {
return true
}
if i := strings.Index(s, "Mutable"); i >= 0 && c.getTypeIDs[s[:i]+s[i+7:]] {
// Mutable and immutable variants share a type ID.
return true
}
return false
}
// Comment from Darwin's CFInternal.h
/*
// Tagged pointer support
// Low-bit set means tagged object, next 3 bits (currently)
// define the tagged object class, next 4 bits are for type
// information for the specific tagged object class. Thus,
// the low byte is for type info, and the rest of a pointer
// (32 or 64-bit) is for payload, whatever the tagged class.
//
// Note that the specific integers used to identify the
// specific tagged classes can and will change from release
// to release (that's why this stuff is in CF*Internal*.h),
// as can the definition of type info vs payload above.
//
#if __LP64__
#define CF_IS_TAGGED_OBJ(PTR) ((uintptr_t)(PTR) & 0x1)
#define CF_TAGGED_OBJ_TYPE(PTR) ((uintptr_t)(PTR) & 0xF)
#else
#define CF_IS_TAGGED_OBJ(PTR) 0
#define CF_TAGGED_OBJ_TYPE(PTR) 0
#endif
enum {
kCFTaggedObjectID_Invalid = 0,
kCFTaggedObjectID_Atom = (0 << 1) + 1,
kCFTaggedObjectID_Undefined3 = (1 << 1) + 1,
kCFTaggedObjectID_Undefined2 = (2 << 1) + 1,
kCFTaggedObjectID_Integer = (3 << 1) + 1,
kCFTaggedObjectID_DateTS = (4 << 1) + 1,
kCFTaggedObjectID_ManagedObjectID = (5 << 1) + 1, // Core Data
kCFTaggedObjectID_Date = (6 << 1) + 1,
kCFTaggedObjectID_Undefined7 = (7 << 1) + 1,
};
*/
func (c *typeConv) badJNI(dt *dwarf.TypedefType) bool {
// In Dalvik and ART, the jobject type in the JNI interface of the JVM has the
// property that it is sometimes (always?) a small integer instead of a real pointer.
// Note: although only the android JVMs are bad in this respect, we declare the JNI types
// bad regardless of platform, so the same Go code compiles on both android and non-android.
if parent, ok := jniTypes[dt.Name]; ok {
// Try to make sure we're talking about a JNI type, not just some random user's
// type that happens to use the same name.
// C doesn't have the notion of a package, so it's hard to be certain.
// Walk up to jobject, checking each typedef on the way.
w := dt
for parent != "" {
t, ok := w.Type.(*dwarf.TypedefType)
if !ok || t.Name != parent {
return false
}
w = t
parent, ok = jniTypes[w.Name]
if !ok {
return false
}
}
// Check that the typedef is either:
// 1:
// struct _jobject;
// typedef struct _jobject *jobject;
// 2: (in NDK16 in C++)
// class _jobject {};
// typedef _jobject* jobject;
// 3: (in NDK16 in C)
// typedef void* jobject;
if ptr, ok := w.Type.(*dwarf.PtrType); ok {
switch v := ptr.Type.(type) {
case *dwarf.VoidType:
return true
case *dwarf.StructType:
if v.StructName == "_jobject" && len(v.Field) == 0 {
switch v.Kind {
case "struct":
if v.Incomplete {
return true
}
case "class":
if !v.Incomplete {
return true
}
}
}
}
}
}
return false
}
func (c *typeConv) badEGLDisplay(dt *dwarf.TypedefType) bool {
if dt.Name != "EGLDisplay" {
return false
}
// Check that the typedef is "typedef void *EGLDisplay".
if ptr, ok := dt.Type.(*dwarf.PtrType); ok {
if _, ok := ptr.Type.(*dwarf.VoidType); ok {
return true
}
}
return false
}
// jniTypes maps from JNI types that we want to be uintptrs, to the underlying type to which
// they are mapped. The base "jobject" maps to the empty string.
var jniTypes = map[string]string{
"jobject": "",
"jclass": "jobject",
"jthrowable": "jobject",
"jstring": "jobject",
"jarray": "jobject",
"jbooleanArray": "jarray",
"jbyteArray": "jarray",
"jcharArray": "jarray",
"jshortArray": "jarray",
"jintArray": "jarray",
"jlongArray": "jarray",
"jfloatArray": "jarray",
"jdoubleArray": "jarray",
"jobjectArray": "jarray",
"jweak": "jobject",
}
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